Cylinder head



Jan. 14, 1930. o, c, KRElS 7 1,743,276

' CYLINDER HEAD Filed Oct. 31, 1927 A TTORNE Y.

Patented Jan. 14, 1930 Y UNITED STATES PATENTOFFICE OSCAR O. KREIS, OF DETROIT, MICHIGAN, ASSIGNOR TO CONTINENTAL MOTORS GOR- PORATION, or DETROIT, MICHIGAN, A CORPORATION or VIRGINIA CYLINDER HIEEAD L-type of engine and other types in which the intake and exhaust valves are located to one side of the engine cylinder although as the description continues it will be apparent that certain other valve arrangements may be utilized within the scope of my invention.

Some years ago it was customary in internal combustion engine practice to construct the cylinder head so as to provide a relatively low compression ratio. Engines of relatively high compression have, of course, been developed for many years but the general practice especially in engines for automobiles and the like, has been along the relatively-low compression lines, except in more recent years.

The present tendency in engines for automotive use is to increase the compressionratio, naturally resulting in constructing the cylinder head with a low ceiling above the piston when the latter is in the dead center position. This is apparent from a brief consideration of the elements involved. For example, it is apparent that the valve chamber must be of a generally uniform volume determined chiefly by the necessary clearance for the valves and the-flow of gases past the valves. Having determined the volume in the valve chamber it remains that in order to obtain the desired relatively high compression ratio the volume of the combustion chamher above the piston must be minimized resulting in a natural and gradual approach of the cylinder head ceiling and the piston. Thus some years ago it was quite common to construct the cylinderhead of substantially equal height above the valves and cylinder, but as compression ratios-increased, the

, clearance volume necessarily diminished, the

cylinder head ceiling above the piston necessarily approaching the piston, this portion of the clearance volume being the only portion capable of reduction as hereinbefore stated.

As a result of the aforesaid evolution in v cylinder head design the resent tendency is toconstruct a. cylinder ead having very small clearance above the piston. Such construction has a very decided disadvantage however, commonly referred to as detonation.

It has been common practice to construct thecylinder head walls, above the combustion chamber, from the standpoint of strength required for the particular metal used.v This is only natural and logical in minimizing the weight and expense of the metal used. I have discovered however, that by materially increasing thewall thickness of thecylinder head the engine detonation will be eliminated resulting in a smooth running engine of high efliciency. As far as I am aware, prior to my invention, there is no teaching in the art for overcoming this embodied in my invention.

Referring to the accompanying drawings illustrating one embodiment of my invention:

Fig. 1, is a section view showing my cylinder head construction, and

head.

In the drawings reference character 10 illustrates the cylinder block or casting having cylinders 11 formed in accordance with the usual practice. .Each cylinder has associated therewith a pair of valves 12 seating \in the block adjacentthe cylinder, one valve serving for exhaust and the other for intake as will be readily understood. In' the L-type engine the valves 12 are positioned generally in the same plane to one side of the associated cylinder; 13 is the piston which at'top dead center may have its top 14 in the plane of the cylinder top 15. The usual sealing gasket 16 is located between the cylinder-endand the cylinder head 17. This cylinder head is provided with the cooling water jacket 18 and spark plug opening 19.

In an engine of the above type the cylinder head has a cylinder roof portion 20 which overlies a portion of the'cylinder and piston, being spaced from the latter by the gasket thickness as indicated at '21. The cylinder head roof then extends upwardly at 22 to provide the necessary passage 23 for the gases relatively between the valve combus'-' Fig. 2 is a bottom plan view of the cylinder problem in the manner tion chamber 24 and the cylinder 11. The cylinder head roof is fashioned to form the valve chamber, enclosing the valves, it being understood that a certain amount of clearance must be left between the cylinder head roof and the valves to provide for the valve lift and additional clearance to provide for an easy flow of gases past the valves 12. It is in an engine with the foregoing general characteristics that my invention relates. Ordinarily the thickness of the-cylinder head wall above the cylinder and valves is constructed in accordance with the strength requirements necessary under operating conditions of the engine, such thickness being illustrated at 25 for example. I have discovered that by materially increasing this wall thickness as at 26 for example, this general type of cylinder head will not give rise to detonation under the most severe conditions of engine operation, the detonating tendencies of such a cylinder head being materially reduced to a negligible factor with the usual fuels and under normal operating conditions.

By way of illustration and not as a limitation of my invention, I will cite a specific example of a cylinder head constructed in accordance with my invention. The engine illustrated has a 2% inch bore and a 4 inch stroke with a compression ratio of 5 to 1, the cylinder head roof thickness indicated at 26 being%% of an inch. The same engine with the usual cylinder head roof thickness of of an inch indicated at 25 was found in practice to give rise to detonation, eliminated by my discovery. I have found that by following my invention engines of compression ratios approximating 6 to 1 may be operated entirely satisfactorily without the otherwise attendant detonation. In fact there seems to be no limit to the compression ratio upper value which may be successfully employed in so far as the factor under consideration is involved.

I do not limit my invention to any fixed dimensional increases in the cylinder head roof thickness since the minimum roof thick ness for any engine can be readily determined by experimentations. I have found that the roof thickness will ordinarily run from approximately of an inch in small engines to of an inch in medium size engines as compared with the usual corresponding roof thickness of approximately & of an inch to of an inch. Of course, the wall thickness may be made greater than these approximate values but such addition beyond a certain point will not add to the smooth running qualities of the engine. A higher compression ratio is frequently used in smaller engines so that a proportionatelygreater roof thickness may be found necessary in the smaller engines.

. As a matter of reference only, the cylinder tion, the fundamental factor being the coni to construct struction of the cylinder head of this type having a roof thickness based on the elimination of tendencies toward detonation in the engine instead of being based on strength qualifications.

My invention will also be found useful in engines having other valve arrangements where the low ceiling is employed above the piston, such for example where the intake and exhaust valves open toward each other.

l/Vhat I claim as my invention is:

1. An internal combustion engine incorporating a cylinder block formed with a cylinder bore, a pair of valves seating in said cylinder block adjacent to the upper end of the cylinder, a piston operating in the cyhnder, said piston at its outer limit of movement having its face substantially in the planeof the top of the cylinder block, a jacketed cyl nder head, and a gasket intermediate the cylmder headand cylinder block, said cylinder head having a roof, a portion of which lies above the piston and substantially parallel and adjacent thereto when the piston is at top dead center, a second portion of the cylinder head roof forming a valve combustion chamber with the valves and cylinder block top, characterized in that at least one of the said cylinder head roof portions exceeds by at least 50% the thickness of the cylinder wall, the cylinder wall thickness being calculated to meet ordinary strength requlrements, whereby tendency toward detonation in the engine is overcome.

2. In an internal combustion engine of the relatively high compression type having a cylinder, a piston in the cylinder, and 00- operating intake and exhaust valves, a cylinder head closing thecylinder by a bounding roof portion lying close adjacent to the piston face when the piston is in its extreme outer position and a second roof portion forming a Valve combustion chamber, the thickness of the cylinder head, roof portions being in excess of approximately 150% of the thickness of the cylinder wall.

3. In an internal combustion engine of the L-head Water cooled type incorporating a cylinder block formed with a cylinder bore, a pair of valves seating in said cylinder block adjacent the upper end of the cylinder, a' piston operating in the cylinder, a cylinder head closing the cylinder by a bounding roof portion lying close adjacent the piston face when the piston is in its extreme outer position and a second roof portion forming a valve combustion chamber, the thickness of the first said cylinder head bounding roof portion being in excess of approximately of the thickness of the cylinder Wall, the cylinder wall thickness being calculated to meet ordinary strength and usage requirements.

In witness whereof, I hereunto subscribe my name this 28th day of October, A. D. 1927.

' OSCAR C. KREIS. 

